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3D-printed reefs at Anholt Offshore Wind Farm

Pioneering test of 3D-printed reefs in Danish waters aims to improve cod population in Kattegat and The North Sea.

For the first time ever 3D-printed reefs are deployed in Danish waters at Anholt Offshore Wind Farm, where PensionDanmark holds a 30 pct. stake.

The World Wildlife Fund for Nature (WWF Denmark) and Ørsted, the operator of Anholt Offshore Wind Farm, have installed 12 3D-printed reefs on the seabed among the turbines of the wind farm, hoping to help restore bio diversity in Kattegat and The North Sea.

The new reefs complement the stone reefs that were established during the construction of the wind farm in 2012 and 2013. The aim is to increase the cod population and in turn contribute to a healthier, more resilient marine ecosystem with improved biodiversity.

”We are very proud to see Anholt Offshore Wind Farm pioneer 3D-printed reefs in Danish waters. Biodiversity is a focal point for PensionDanmark and if this innovative initiative can improve biodiversity in the marine ecosystem while the wind farm is producing sustainable power we have a win-win-situation for all concerned,” says Torben Möger Pedersen, CEO at PensionDanmark.

In recent decades, attention has been drawn to the fact that the extensive overconsumption of sea and marine resources has enormous consequences. Globally, these consequences include dwindling fish stocks, oxygen depletion near the seabed, eelgrass quantities in the oceans being halved in the past 100 years, and a lack of habitats for marine life.

Cod is an important top predator, meaning it helps balance populations of other marine life and the wider ecosystem, enhancing overall biodiversity. When cod disappears, the population of their prey – such as the beach grab – will grow. As a result, seagrasses decline: the crabs eat both the seeds of the eelgrass and many of the snails that themselves keep the eelgrass healthy by cleaning it of algae.

This is a problem as eelgrass in itself is of great importance for both biodiversity and the climate. It provides important habitats for sea life such as small and juvenile fish, it produces oxygen for the sea, and it stabilises the seabed. Crucially, it also very effectively stores carbon in its root network, preventing it from ending up in the atmosphere and contributing to global temperature rise.

“The ocean holds vast potential to help meet our climate goals. Improving ocean health and restoring marine biodiversity is fundamental to addressing biodiversity loss and the climate crisis. As governments around the world are ramping up ambitious plans to grow renewable energy capacity, offshore wind will take up more space. At Ørsted, we believe action on climate and nature can and must go hand-in-hand, and this exciting project together with WWF Denmark is one of many we’re testing out globally to seek the best solutions to make our ambition of a net-positive biodiversity impact a reality,” said Filip Engel, Vice President of Sustainability at Ørsted.

The reefs are made from 70% sand and 30% volcanic ash and clinker. These are natural materials and will not be harmful to the surrounding environment, even if parts of the reefs should erode over time. Each of the 12 reefs weighs between 200 and 550 kg and they are one square meter in size with a height of one meter.
WWF has good experience with 3D-printed reefs, which they have already used in a project in the Dutch part of the North Sea.

“Marine biodiversity in Denmark is under heavy pressure, and today there are 90 % fewer cod in the Kattegat than in 1990. Action is needed – and urgently. We must give nature and wildlife a hand, while trying to solve our climate crisis by expanding our renewable energy production at the same time. To solve the nature crisis, we must leave nature in better shape than before. That’s why we’re very excited that we, together with Ørsted, can test the new, unique 3D-printed reef structures here in Denmark for the first time,” says Bo Øksnebjerg, Secretary General, WWF Denmark.

Watch a video on the new reefs here.

Facts about Anholt Offshore Wind Farm

  • Anholt Offshore Wind Farm consists of 111 wind turbines with a total capacity of 400 MW. This corresponds to a completely carbon-free power consumption of more than 1 million Danes.
  • Once completed in 2013, the wind farm was the world's largest.
  • The farm is operated by Ørsted that holds a 50 pct. stake, with PensionDanmark (30 pct.) and PKA (20 pct.) as minority stakeholders.
  • During the construction of the wind farm, stone reefs of various sizes were established to provide better living conditions for marine wildlife. Today, the stone reefs are teeming with life.